Casting to a vector of pointers - c++

Question

I have a vector of shared pointers of a pure virtual class IObserver (observers), the vector is a class which inherits IObserver. There is also a second class which inherits IObserver, HomeOwner. I want to cast Homeowner objects to the observers vector, so I can send them to the functions in SecurityStatus but not sure how I go about it. I'd like to do it behind the scenes rather than in the main program. The declaration for both is below.
Thanks!
#pragma once
#include "IObserver.h"
#include "HouseSecurity.h"
#include "SensorInfo.h"
#include <vector>
#include <numeric>
#include <algorithm>
#include <string>
#include <iostream>
using namespace std;
// concrete observer
class HomeOwner : public IObserver{
SensorInfo currentSensorState;
string myName;
string myPhoneNumber;
string myEmail;
HouseSecurity &house;
public:
void Update();
void New();
HomeOwner(string, string, string);
};
#pragma once
#include "IObserver.h"
#include "HomeOwner.h"
#include <vector>
#include <numeric>
#include <algorithm>
#include <string>
#include <memory>
using namespace std;
// subject
class SecurityStatus{
vector <shared_ptr<IObserver>> observers;
public:
void AttachObserver(shared_ptr<IObserver>);
void DetachObserver(shared_ptr<IObserver>);
void NotifyObservers();
};